Art of light-sensitive photographic materials



' therein n very small amounts.

Patented Sept. 21,1926.

U N i S T Banner: 1*. runnnr'r, or GREECE, NEW Yon' Assieivon .ro nAsrAn' KODAK comram,

OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

ART or nronr-snnsrrivn rnorooaarmoiun'rnnmrs.

Ho Drawing.

' This invention relates to the art ofphotographic materials.

One object of the invention is to provide photographic sensitizingmaterials capable of greatly increasing the light sensitiveness ofphotographic emulsions especially of the developing-out type, even whenincorporated Another obto provide such materials in concenject is andsufficiently purified conditlon so trated stances in which they aremixed. A still to give density incorporated therewith.

f further object is. to'provide a process for obtaining said material insaid desirable condition.

Another, object of the invention is to provide photographic emulsionssuch as devel-' oping-out emu'lsions,'having new and improved propertiesbecause'of'the use or presence therein of my independent sensitizingvmaterial. Still another object of my invention is to provide aprocessin which my said sensitizing material is used to improve vphotographic emulsions, especially developing-out emulsions. as regardslight sensitivenes's, by which term Iinclude their ability to 7 give theearliest visible impression or image with the minimum exposure or theirability after a given exposure or both, the usual photographic fluidtreat: ments. being used in preparing such impression or'image. L

A further object of the invention is to provide a colloid product, suchas treated gelatin, the usefulness of which for forming light sensitivephotographic emulsions; notbly developing-out ones, is increased" andcontrolled by my said sensitizing material Another object of i theinvention is to provide a corresponding process for making saidintermediate colloid product.

Other objects are,-to increase the sensitiveness of photographicemulsions, particularly developing-out emulsions, while wholly orpartially dispensing with expensive or long and uncertain so-calledripening methods;- toenable the use of a type of gelatin having.desirable physical qualities inmaknessof photographic emulsions,particularly Application filed June 6, 1924. Serial No. 718,409.

developing-out ones, the grain characteristics of which have alreadybeen determined; to increase the general light sensitiveness of suchphotographic emulsions throughout the spectral ranges to which they arenormally sensitive; to make such photographic emulsions of standardlight sensitive characteristics with gelatinswhieh normally do notproduce emulsions having such characteristics; to make, as intermediatesin the manufacture of photographic emulsions, gelatins of standard lightsensitiveness giving power out of gelatins which do not normally havethe power of giving such standard sensitiveness to emulsions, such asdeveloping-out ones made from them. Further objects will hereinafterappear. r j

I have found a photographic sensitizing material, very small amounts ofwhich greatly, increase the light sensitiveness of photographicemulsions, such as those, of the developing-out gelatino-silver-halidetype, for example. This material I have found out how to obtain inconcentrated forms, so that when incorporated in such emulsions orgelatins for such emulsions, it produces its sensitivity-increasingaction without harmfully diluting said emulsions or gelatins, orimpairing thephysical properties of them. In other word s, the use of mysensitizing material furnishes a safe, practical,

and largely independent way of controlling the properties of emulsionsin addition tomy invention in connection with such emulsions; but itwill be understood that my invention is not restricted to this exampleexcept as indicated in the claims.

The first operation. in practising my inventionis the preparation of thesensitizing material. Be ng of biochemical origin, it is preferablyconcentrated, or separated from the organic tissues, or bulky productsfrom such tissues, with which it is associat ed. For example, itoriginates in the tissues that yield gelatins and is carried into thelatter during their manufacture. Such 'gelatins especially those.prepared for photog'raphic use, are, therefore, useful sourcesfromwhi'ch my sensitizing material may be derived. Not-all gelatinscontain it to the same extent. Totest whether any particular kind oravailable batch 'of gelatin will be a sufiiciently fruitful source ofsensitizer, a small sample of it can be extracted by the methodhereinafter described and the ex tract added to an emulsion, such as theone hereinafter disclosed. If the sample sensitizer causes a. goodincrease in light sensitiveness of the emulsion, then the kind ofgelatin or whole batch of it can be extracted. This extraction of asample and trial in a known emulsion provides a ready test of the rawmaterial; but'in the absence of test,

practically any gelatin which can be used 1 out the invention, water.

' preferably distilled-is added to the gelatin at a moderatetemperature, say 85 F, for instance. The amount of water 1s convenientlyin aslight excess (say 10 to 20 per' cent) over the amount absorbed bythe gelatin to swell it. at said working temperature.

\ 1101 as a preservative.

This is allowed to stand or soak at said temperature fv r several days,two or three being usually 'su cient. During this time evaporationshould be lessened or prevented, such as by keeping the wet gelatin in aclosed vessel. Harmful bacterial action can be prevented by adding asmall amount of phe- Agitation of the wet gelatin during the soaking isvery desirable. Vigorous shaking of it at intervals in thevesselwhichcontains it is one satisfactory way of doingthis;

At the endof the soaking period, the encess watery solution, which isoften somewhat viscous,can be poured off from the gelatin.- The yield isimproved if some of the liquid also bepressed out of the gelatin,

say by centrifuging it. The liquid, which hastakeitup the necessarysubstances from Y the gelatin,' constitutes an excellent sensitizingmaterial. Water may,, however, be evaporated from it, making .it stillmore con .centrated, such evaporation beingconducted during the soaking,or afterward, or both. The ultimate paste, and even the substantiallydry material, reached by. continued drying, likewise constituteconcentrated sen- .sitizing materials. Such materials are, in

general, almost-colorless. There are'usually' 3 some breakf'downproducts-of gelatin in the materlal whetherthe latter. be aqueous ordry; but it is substantially free from unhydrolyzed gelatin. Thesensitizing materialv is, therefore, for all practical purposes, freedfrom the bulk of organic tissues and their bulky derivatives, such asgelatin, with which it was initially associated. Stated in another way,the proportion of active sensitizing bodies in the final material islarger than they proportion .in the sources from which it is prepared.This makes it especially useful because it can be incorporated intoemulsions without undesirably diuse less than 100% excess "of liquid.But instead of using onlya small excess of water during the soaking, alarge excess may be substituted and when the resulting dilute liquid ispoured off from the soaked gelatine, it may be concentrated by removalof enough water until it gives a sufficiently strong sensitizing action.It withstands boiling butis preferably concentrated below boilingtemperature at either atmospheric or reduced pressure. After evaporationto substantial dryness, the residue may be again taken up in waterwiththe sensitizing property still present. Investigation indicates thattheaqueous solution is not a true one but is colloidal. The fact thatthe sensitiz: ing propertyremains in the dry residue and in the aqueoussolutionshows that the sen sitizing material has a very usefulstability. It is generally neither markedly alkaline nor acid althoughit withstands both dilute acids and alkalis' and can be used with themin making emulsions.- I classify it as organic or biochemical indistinction from inorganic material such as ammonia, silver nitrate,etc., for example; While it keeps Well,

bacterial action can be prevented by a'little- I sions-or in colloidsfor emulsions orboth.

It gives; additional light'sensitiveness to various kinds of emulsionshaving different speeds and other distinctive characteristics.

While it may be added at'diiferent stages of emulsion manufacture or bemixed with emulsion ingredients, either organic or inorganic, beforetheyare mixed into the emula sion, nevertheless it can be veryconveniently mixed into the emulsion when the latter is complete, readyfor coating. With the grain characteristics, such as sized1stribution,ietc.,

properties by ace-73c already determined, and the other physical andphotographic properties of the emulsion already taken care of at thisstage,,I can practical independently increase its light sensitivenesswithout impairing said other adding As will be the art, the proportionof rial added to the emulsions will vary accordunderstood by thoseskilled in .ing to the nature of the latter, according to theconcentration of the sensitizing material and according to creasev in'the light sensitiveness which is desired. It can be readily adjust---ied .by trial on samples of the emulsion. When the sensitizingmaterial is made as above descrlbed using a 10% excess of water,

which is necessary a'useful-proportion for trial is'15 parts ofsensitizing solution to 1000 parts by volume larger proportions theemulsion'is although they may be otherwise satisfactory, theirsensitiveness can readily be brought up to standard by mixing inmysensitizing material, the'proportion ryarylng with amount of increase toproduce a uniform product. Emulsions having almost no pracof the 0 herqualities desired in a photographic sensitive by addition tical lightsensitiveness but having enough mulsion can be made usefully light ofmymaterial. Thus,

-im'y sensitizing material is useful in connec- L tion with6111111810118 sitivenessand those having almost no 1n1t1a1 The increasein SGIlSltlVGHGSS .sensitiveness.

having good initial senman be: effected in one step by thoroughlystirring all of the sensitizing material into the flowableemulsion atone time; or it may be incorporated a little at a time in successivesteps. gThe following example illustrates how a light sensitivephotographic emulsion may be prepared and improved by the aid of mysensitizing material. Of course, my invention is 'not restricted to thisillustration but is applicable in the cases of .thevery large number ofwidely different. emulsions in this art. The emulsion inafter' describedforming operations hereare along the lines .of known {practice,-see, forinstance, Die Photographie mit Bromsilber Gelatin by J.. Eder, publishedin Halle, Germany, in

1903b; Wilhelm Knapp as Part 111. or I Eders FAnsfuhrliches Handbuch derPhothe parts being by weig tographie. v The twojfollowingsolutions are'made'up,

A. 900 parts of silver nitrate in 9,200 parts I of water.

the concentrated and purified sensitizing material described above.

sensitizing mate-' the amount of m',

- broken up, as byshredding,

. emulsion. For example,

melted and there 1S thoroughly mlxed 111130.

B. 690 parts of potassium bromide and 50 parts of potassium iodide in6,100 parts of water along with 300 parts of gelatine.

- In mixing B, the halide saltsare first dissolved, the water and thegelatin-then added to the salt solution. warmed, say to 140 ample; andthe silvernitrate solution gradually added to it with constant stirring.It is preferable to warm solution A before adding it to B, say tov150F., or 160 F., for instance.

Solution 13 is'then F., or 150 F., for exiVhen solution A has beenthoroughly incorporated in solution B, there are then added 43 parts ofstrong ammonia previously dissolved in 900 parts of water. The emulsionformed by these operations is allowed to stand fora short-time, say 15minutes to a half hour, for example. Then, 1050 parts of gelatin aredissolved in it with thorough mixing.

until it sets to a firm jelly-" The latter is for. instance, andthoroughly washed to remove soluble salts,'such as potassium nitrate andany excess potassiumhalides. The water is,,.of course, coolenough not tomelt the pieces of emulsionjelly. ,The washed emulsion is next remeltedtoy100 F., and 1050 parts of water soaked gelatin are thoroughly mixedinto it, the temperature then being raised,

say between120 E, and 150,F., for in-' stance, forashort; time, say afew minutes.

It is then. cooled and set. It is of thelammonia or alkaline type ofemulsion.

y-My sensitizing material may be usefully incorporated at any stage ofthe above described process of,.-prepa'ring the emulsion, even beingpre-miredwith solutionsv A or' B or 'with the ammonia or with thegelatin at the initial stagesh It is convenient to add it to theotherwise complete melted emulsion pr or to coating on supports at thefinal stage in the process of preparing the the emulsion is reit 15parts by volume of my sensitizing material (say theaqueous'preparationformed as above describedby using10% excess of water over that ab orbedby the, gelatine) for each 1000 parts by Volume of emulsion. Since theactual sensitizing. bodies are only a smallpart of the colloidizedsolids in such preparation and since such solids total. as only .a smallproportion ofsaid liquid preparation bodies are very useful when addeilmuch less-than one part per thousand of emulsion by weight, in factoften less than one part'in that the additionof this preparation does nosubstantiallv dilute the emulsion, being of the order of' twoper 'centorless.

" With its light; sensitiveness increased by The emulsion is nextcooled,such as byfkeeping in a cool place,

it follows that the actual tens tizingin even-- ten thousand. It 3will-:be noted my material,-the emulsion, being melted to the desiredflowability, is coated on its support, such as glass, film, paper,etc.,in the well known way. It isconvenient to control and check theprocess by coating samples of the emulsion before and after the additionof my sensitizing material, the coated specimens being tried outphotographically by any well known sensitometric test, or even bycomparative camera exposures on the same subject. Of course, the

usual precautions are observed during the,

emulsion making and coating process, such as the use of non-actinic orsafe light, cleanness of vessels and air, etc.

The different gelatins sold for photographic emulsion making may be usedin the example given above, hard ones being very useful. Thetemperatures given are, of course, adjusted if the particular gelatinemployed has physical properties, such as melt ing and setting points,which deviate considerably from the usual ones, such adjust ment being amatter of routine control.

Instead, however, of using gelatins which give emulsions of useful butlower sensitiveness even before the addition or my sensitiz ingmaterial, an almost inert ge atin may be employedone which forms anemulsion which produces a developable image only after impracticallylong exposures, and then does not yield an image of desirabledensity, Agelatin which forms such a nearly inert 'emulsion may be prepared in theway de-.

scribed under the heading Preparation of ash-tree gelatin, on pages 1858and 1859 of the Journal-of the American Chemical Society, September,1922, Volume XLIV. No. 9, being'part ofan article by Sheppard, Sweet,and Benedict on Elasticit of purltied gelatin jellies as a function ofiydrogenion concentration.- Emulsions-of impractically low lightsensitiveness made by the above described process from such preparedgelatin, are transformed by my sensitizing material into emulsions whichgive developable images of excellent density after usefully briefexposures. I have, for example, been able to increase the lightsensitiveness of such low-sensitive. emulsions over. twenty times, theexposures for a given subject being cut to less than one twentieth ofthe original one and the image density being made excellent by acorresponding gain. Increases of the same general order of magnitude arema 'le'when my sensitizing material is added in similar proportions toemulsions which are'made from normal photographic gelatins or mixturesof such normal gelatins with said almost inert gelatin, and-alreadyhaveuseful but lower initial sensitiveness Different )ercentages ofsensitizer produce correspondingly di'li'erent increases. The increasesin'developing-out emulsions appear upon the usual developing operations.Customary pyro or metoLhydrochinon alkaline developers are as good asany for example.

For testing the power ofsensitizing material, and almost inert emulsionmade, as above described, from said prepared gelatine isalso veryuseful. Fifteen parts by Volume of the sensitizing liquid can be addedto 1000 parts of such emulsion and the.

mixture coated and tested photographically in comparison witli'aparallel sample of the unsensitized emulsion. While the addition ofsensitizing material as a liquid is most convenient, the residueobtained from evaporating oil the water from said liquid can be addeddirectly to the emulsion. In addition to having increased sensitiveness,emulsions containing my sensitizing material have improved stability orkeeping qualities because of the purification of said material.

My sensitizing material maybe incorpo rated 'mto gelatin with whichphotographic made from the mixture have increased light sensitiveness.as compared with those made from corresponding unstrengthened gelatin.

The proportion of sensitizing material is,

of course, adjusted to give the desired control of the sensitiveness ofemulsions made vfrom the gelatin, the total sensitizing inaterial. inthe strengthened gelatin being thus brought above normal. It isespecially effective when used in making emulsions having, at leastslight alkalinity.

I My sensitizing material acts as a so-called "chemieaP sensitizerinstead of an optical sensitizer. In other words, it increases thegeneral sensitiveness of developingout photographic emulsions in whichit is incorporatedythat is, to-light of substantially the same wavelengths as those to which the emulsion is sensitive before my materialis added; instead of merely increasing sensitiveness to light of wavelengths the same or nearly the same as those absorbed by it. It haserties, unlike dyes. The general sensitiveness is increased; that is,throughout the normal spectral range of the emulsion instead of at onlythose points corresponding to the strong spectral absorption of'dyesensitizing material. My inaterial is effective in increasing thegeneral sensitiveness of orthochromatic, panchromatic, .X-ray, and allspecial emulsions, as well as the ordinary or non-color-se'nsitizedones. It is preferpractically no coloring. 'propably addedseparatelyorindependently ot' the sensitizing dye generally, but notneces- Sarily before any dye. It is especially effective in emulsions ofthe ammonia or alkaline type. b

In the example given above the steps of treating with ammoniaand'warming of the emulsion just before its final setting im-. prove thephotographic. properties of the emulsion, especially when thelatter ismade fromhard gelatins. While one or both of 1 them may. be omittedLpreter to use both,-

' ployecl. The

in other words, my sensitizing material can act by itself' toincreasethe light sensitiveness; but ripening steps are preferablyemetiect of either or both of such s to help increase the lightsensitivesteps,

. ness ofithe emulsions and thus give a stronger lnltla-l sensitizedcondition which is mul 'pensed with;

trated when it-gives a useful eiiect without have the' wide st practicaluse,

VVhile I have ployed, such as curring harmfully diluting the emulsion.It does not act asa photographic developer.

. I have described gelatin emulsions because at the present time theyare the ones which especially the developing-out -ones. Moreover, theyform the best medium for testing my sensitizing materials, thecharacteristic action of such materials on such emulsions being one ofthe best identifying criteria of such sensitizing materials. -tures of.them with each other or with gelatin, Where their nature admits suchmix- Other organic colloids and 1111K tures, maybe used in making lightsens tive emulsions which can be improved by adding my sensitizingmaterial. Albumens, agaragar, gums, such as gum arabic, cellulpsicderivatives such as collodion, are instanbed.

disclosed the use of my se'nsitizer in connection .with such sensitivesubstances as silver bromide and silver iodide. other light sensitivesubstances can be em- K silveri chloride, alone or mixed with one ormore of the others.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is: I V

' 1. A substantially colorless organic hotographic sensitizing materialderived .rom animal tissues, said material having the property ofincreasing-the light sensitiveness of photographicgelatino-silver-halide emulsions and being in a eoncentrated' 'tormsubstantially free from said tissues and from :bulky products thereof.

A biochemical sensitizing material ocin natureyvith gelatin and havingthe property of increasing the light sensitiveness of photographicgelatino-silverhalide emulsions of the alkaline type and being inconcentrated form substantially free iromits associated gelatin.

3. A biochemical sensitizing material derived from animal sources whichacts to increase the general light sensitiveness ofgelatinQsiIVer-halide emulsions of the alkaline type, when it isincorporated therein, without acting to alter the grain sizecharacteristics thereof, said material being in concentrated formsubstantially free from its normally associated bulgy unhy'drolyzeddiluents.

4. A concentrated, purified, substantially colorless biochemicalsensitizing material, which is capable, even in, the absence of dyes, ofincreasing the light sensitiveness of gelatino-silver-halide emulsionswithout interfering with the grain characteristics thereof, saidmaterial being substantially free from normally associatedunhydrolyzedgelatin. v

5. A sensitizing material from biochemical sources carried in a liquidwhich is harmless when mixed in light sensitive emulsions, said materialhaving the property of increasing the light sensitiveness ofgelatinosilver-halide emulsions, in which it is incorporated, evenin theabsence of dye and inorganic sensitizers, said materialhaving, per unitvolume, greater sensitizing power than said sources.

6. A biochemical material derived from the same sources as photographicgelatin and possessing the light sensitizing principle of photographicgelatin in concentrated form substantially free from the bulk of itsnormally associated gelatin. H

7. A light sensitive emulsion comprising a colloid, particles ofphotographic sensitive salts suspended therein, and an independentorganic sensitizing material difierent from said colloid upon which atleastpart of the general lightsensitiveness of the emulsion depends.

8. A photo no-silver-hali e light sensitiveness comprising a mixture 0aphic developing-out gelatiemulsion of relatively high the constituentsof a gelatino-silver-halideemulsion of lower light sensitiveness and anindependent biochemical sensitizing material upon which depends thedifierence between said lower and said high light sensitlvfieSS.

.9, A photographic gelatino -silver halideemulsion of the alkaline typecomprising a mixture of gelatin, silver halide particles, and abiochemical sensitizing material, sub-. stantially free from itsnormallyassociated bulky impurities, which increases the light sensitiveness ofsaid emulsion.

10. A photographic gelatino-silvershalide emuls on comprising asuspension in-gelatin of silver halide particles, and an independentbiochemical sensitizing extract upon which at least part of the lightsensitiveness of said emulsion depends, the volume of said extract beingless than the order of 2 per cent of the total volume of the emulsion.

11. A. photographic gelatino-silver halide emulsion of relatively highlight sensitiveness substantially free from dye sensitizers, comprisingamixture of the constituents of a gelatino-silver-halide emulsion, havindetermined grain size characteristics and lower light sensitiveness, andindependent biochemical sensitizing material upon which depends thedifierence between said lower and said high light sensitiveness Whilesaid grain size characteristics remain substantially constant.

12. A photographic gelatino-silver-halide emulsion of the alkaline typecomprising a suspension in gelatin of silver halide part cles and anindependent biochemical sens tizing material, the percentage of lightsensitiveness due tosaid material. being greater than the percentage ofthe total volume taken up by said material. 13. A photographicgelatino-silver-hahde emulsion comprising a suspension in gelatin ofsilverhalide particles and an independent biochemical sensitizingmaterial, the prpportion of the light sensitiveness of said emulsion dueto said material being of the order of magnitude of 95 per cent, Whilethe volume of the material is of the order of magnitude of 2 per cent ofthe volume of the emulsion.

14. A photographic gelatino-silver-halide emulsion comprising theconstituents of a gelatino-silver-halide emulsion of a lower lightsensitiveness of the order of one-twentieth of the light sensitivenessof the first named emulsion and an independent biochemical sensitizingextract upon which the greater light sensitiveness of the first namedemulsion depends, said sensitizing extract being substantially free fromeffect upon the non-photographic qualities of said emulsions.

15.. A photographic gelatino-silver-halide emulsion substantially freefrom sensitizing dye comprising a mixture of gelatin, silver halideparticles, and an independent organic sensitizing material upon which atleast part of thelight-sensitiveness of said emulsion depends, saidmaterial being substantially free from effect upon the non-photographicqualities of said emulsion.

16. A. photographic gelatino-silver-halide emulsion comprising gelatin,silver halide particles suspended therein, and an independentbiochemical sensitizing extract upon which at least part of the lightsensitiveness of said emulsion depends, the physical properties of saidemulsion which correspond to the physical properties of said gelatinbeing substantially unaltered by said sensitizing extract.

17. A photographic gelatino-silver-halidc emulsion havingcharacteristics of manufacturing standard comprising the constituents ofa gelatino-silver-halide emulsion of substandard light sensitiveness butotherwise of standard characteristics and an independent concentratedbiochemical sensitizing material upon which the difierence between saidsubstandard and standard light sensitiveness depends, the othercharacteristics being substantially independent of said sensitizingmaterial.

18. A photographic gelatino-silvenhalidc emulsion comprising a mixtureof gelatin, silver halide particles, and an organic sensitizing materialupon which at least part of the light sensitiveness of said emulsiondepends irrespective of dye sensitizers, said material beingsubstantially free from bulky colloids.

19. A photographic gelatino-silver-halide emulsion having lightsensitiveness over a definite spectral range and having definite grainsize characteristics, said emulsion comprising the constituents of agelatino-silverhalide emulsion having substantially the same definitegrain size characteristics but having a relatively lower lightsensitiveness over said spectral range and a sensitizing material uponwhich depends the difference in light sensitiveness between the firstnamed emulsion and said second named emulsion over said spectral range,the grain size characteristics being substantially independent'of saidsensitizing material.

20. A photographic colloid-si-lver-halide emulsion comprising a colloid,silver-halide particles suspended therein and a biochemical sensitizingmaterial different from said colloid upon which the general lightsensitiveness of said emulsion depends, the ratio of said material tosaid silver halide being substantially independent of the ratio of saidcolloid to said silver-halide.

21. A pl'iotographic gelatino-silver-halide emulsion comprising gelatin,silver halide particles suspended therein and a sensitizing materialupon which a large part of the light sensitiveness of said emulsiondepends independently of dyes, the ratio of gelatin to silver-halidebeing substantially unaffected by said material.

22. In the process of preparing a photographic emulsion, incorporatingtherein a sensitizing material derived from animal tissues but inconcentrated form substantially free from said tissues and from bulkyproducts thereof, said material increasing the light sensitiveness ofsaid emulsion.

23. In the graphic gelatino sensitivesilver salt emulsion. of thealkaline type, incorporating therein a biochemical sensitizing materialin process of preparing a photoconcentrated form substantially free fromgelatin to increase thelight sensitiveness of said emulsion.

2%. In the process of preparing .a photographiccolloid-sensitive-silver-salt emulsion,

graphic biochemical colloid-sensitive-silversalt emulsion, incorporatingtherein a sensi tizing extract different from said colloid and obtainedfrom biochemical sources, the said extract, per unit volume, beinggreater than that of said sources, to increase the light sensitivenessof said emulsion.

26. In the process of preparing a photographiccolloid-sensitive-silver-salt emulsion, incorporating thereinindependently of any dye sensitizers an organic sensitizing material inconcentrated form substantially free from bulky dilueuts, said materialincreas-,

ing the general light sensitiveness of said emulsion.

27. In theprocess of preparing a photograplnccolloid-sensitive-silver-salt emulsion, incorporating thereinseparatelyfrom dyes 'a biochemica-l sensitizing material in concentratedform substantially free from nonvolatile diluents, said materialincreasing the general light sensitiveness of said emulsion Withoutacting to increase the size of the grain thereof.

28. In'the process of preparing a photographic developing-out gelatinosilver-halide' emulsion of the alkaline type incorporating therein anorganic sensitizing finaterial in con-.entrated form substantially freefrom unliydrolyzed gelatin, said material increasing the generallightsensitiveness of said emulsion.

29. In the process of preparing a photographic gelatino-silver-halideemulsion incorporating therein a sensitizing material from biochemicalsources, having greater sensitizing power, per unit volume, than that ofsaid sources, said material increasing the light sensitiveness of saidemulsion without increasing the grain size thereof.

30. In the process of preparing a photographic gelatino-silver-halideemulsion of the alkaline type, incorporating therein sensitizingmaterial which occurs in dilute form in organic sources and iscontentrated to; be more active, volume for volume, than :said source,said material increasing the general light seflsitiveness of saidemulsion.

' 31. Intlie process of preparing a photographic gelatino-silver-l alideemulsion, incorporating therein separate from any sensithan onethousandth the said material 4 gelatin, said material increasing the;

general light sensitiveness of said emulsion without acting to increase.the grain size thereof.

33. In the process of preparing photographic gel atino-silver-halideemulsion, the steps of taking up a concentrated organic sensitizingmaterial, independent of dye and inorganic sensitizers, in a liquidvehicle which can pass without harm into such emulsion, andincorporating the liquid carrying the material into the emulsion.

34. In the process of preparing a photographic gel-atino-silvcr-halideemulsion, in-.

corporating therein aconcentrated organic sensitizing-Amaterial,substantially free from bulky diluents, which increases the lightsensitiveness of said emulsion irrespective of dyes and inorganicsensitizers.

35. In the process of preparing a photographic gelatiiio-silver-halideemulsion, incorporating therein a sensitizin extract from biochemicalsources and aving a higher sensitizing power per unit volume than saidsources, said material increasing the light sensitiveness of saidemulsion in addition to etiects of dyes and inorganic sensitizers.

36. In the process of preparing photographiccolloid-sensitive-silver-salt emulsions, incorporating therein anorganic sen sitizing material which greatly increases the general lightsensitiveness of said emulsion even in the absence of dyes withoutsubstantiallydiluting the emulsion, theactivesensitizing bodies in saidmaterial being less weight of said. emulsion.

37. In the process of preparing photographic gelat-inmsilver-halideemulsions of the alkaline type, incorporating thereinorganic-sensitizingmaterial which causes an increase in the light sensitiveness of saidemulsion, the active bodies in said material being less than onethousandth the Weight of said emulsion.

38. "In the processof -manu-facturing a. photographic emulsion,extracting from a biochemical source a non-dyeing sensitizing materialin a form substantially free from. bulky associateddilue-nts, andincorporating sufficient of said material .and a different biochemicalcolloid in preparing saidemul-. sion to increase the lightsensitive-ness ot the latter. i

' Q44. In the.

39; In the process of manufacturing a' photographic biochemicalcolloid-sensitivesilver-salt emulsion, extracting fromorganic tissues asensitizing material different from said colioid and in concentratedform substantialy free from" said tissues and bulky derivatives thereof,and incorporating sufficient of said material in preparing said emulsionto increase the light sensitiveness of the latter. 1

' 40. In the process of manufacturing a photographicgelatino-silver-halide emulsion, extracting from a gelatin source asensitizing material in concentrated form and adding said material tosaid emulsion.v

41. In. the process of manufacturing a photographic biochemicalcolloid-sensitivesilver salt emulsion, extractingfrom a biochemicalsource a sensitizing material different from said colloid in which theconcentration of active sensitizing bodies is greater than in saidsource and incorporating suflicient of said material in preparing saidemulsion .to increase the light sensitiveness of the latter,

42. In the process of manufacturing a photographic gelatino silverhalide emulsion, extracting from .a biochemical source a sensitizingmaterial in concentrated form, and incorporating-in preparingsaidemulsion sufficient of said material to increase its lightsensitivenss, said sensitizing material being free from effect on thegrain sizecharacteristics of said emulsion. L

43. In the process of manufacturing a photographicgelatino-silver-halide emulsion, extracting from a biochemical source asensitizing material in concentrated form and incorporating in preparingsaid emulsion sufiicient of said material to increase its lightsensitiveness' irrespective ofthe action of dyes and inorganicsensitizers. I

process of manufacturing a photographic gelatino-silver-halide emulsion,extracting from a biochemical source a concentrated sensitizing materialand incor oratin said material in said emulsion .corporatingapproximately 2 chemical non-dyeing to increase the light scnsitivenessthereof,

thefproportion by volume of'said material v Leing of the orderofmagnitudc of two per cent.

45. In the process of manufacturing a photographicgelatino-sllver-halide emulsion, extracting from a biochemical sourceaconcentrated sensitizing material and inper cent by volume of saidmaterial in said emulsion, the material increasing the light'scnsitiveness' of said emulsion approximately 20 times.

L6, In the process of manufacturing a photographic emulsion, extractinga, biosensitizing material away fron'iat least part of its associatedbulky impurities, by treatment with a fluidvehicle, and incorporatingsufficient of the extract and a different biochemical colloid inpreparing said emulsion to increase the light sensitivencss thereof47.'In the process of manufacturing a photographic biochemicalcolloid-sensitivesilver-salt emulsion, treating an animal sourcecontaining sensitizing materialassociated with bulky 'diluents with afluid into which said IllfitllfihSPI'GitdS more rapidl than saidimpurities until said material 1s concentrated in said fluid and freedfrom at least part of said diluents, and incorporating suiiicient of thepurified extract thus obtained in said emulsion to increase the lightsensitiveness thereof.

48. In the process of manufacturing photographic gelatino-silver-halidcemulsion, treating a. biochemical source containing a sensitizingmaterial and bulky colloid diluents with a fluid into which saidmaterial spreads more rapidly than said diluents until an extract ofmaterial in'said fiuid'is obtained separating at least part of saidfluid from said extractvand incorporating sufficient of said extractinsaid emulsion to increase the light sensitireness thereof.v

49. In the process of .manufacturing a photographicgelatino-silver-halide emulsion, extracting with water from a-gelatinsource asensitlzing material, and adding suiiicient of said aqueousextract to said,

emulsion to increase the thereof;

5O. In the process of manufacturing a photographic biochemicalcolloid-sensitivesalt emulsion of higher sensitiveness the steps offorming a biochemical colloid-sensitive-salt emulsion of relativelylower light sensitiveness, extracting from an animal source asensitizing material, and incorporating s'uflicient of said matcrial insaid emullight sensitivcnas sion of lower light sensitiveness, tochangeemulsionof lower light sensitiveness sufli cient of said materialto change it nto said emulsion of higher light sensitiveness, said grainsize characteristics remaining substan-v tially constantQ p 52. In. theprocess of manufacturing a photographic biochemicalcolloid-sensitivesilver-salt emulsion of relatively higher light isensitiveness, forming a biochemical colloidsensitive silver-saltemulsion of lower lightsensltiveness and having a definite ratio ofextracting a biochemical sencolloid to salt, sitizlng' material from abiochemical source,

and adding suflicient of said sensitizing material to said emulsion oflower light sensitiveness to change it to said emulsion of higher lightsensitiveness without substantially altering said ratio.

53. An intermediate free from silver salts and halid salts for use inmaking photographic emulsions comprising an emulsionforming colloid andan independent biochemical sensitizing material difi'erent therefrom andincorporated therein, said material being substantially free from itsnormally associated bulky diluents, said intermediate havingthe propertyof forming emulsions of higher light sensitiveness than those formedunder parallel conditions from said colloid without the material.

54. An intermediate for use in making photographic emulsions comprisinga biochemical emulsion-forming {colloid and an independent biochemicalsensitizing material difierent from said colloid incorporated therein,said material being derived from a biochemical source but containing ahigher concentration of active sensitizing bodies.

than said source, sald intermediate having the property of formingemulsions of'higher light-sensitiveness than those formed underparallelconditions from said colloid without the material. v V p r 55.An intermediate for forming photographic gelatino-silver-halideemulsions comprising a mixture of gelatin and an independent sensitizingmaterial from a gelatin source, said material being substantially freefrom its normally associated gelatin, and said intermediate having theproperty of forming gelatino-silver-halide emulsions of greater generallight sensitiveness than those formed under parallel conditions fromsaid first named gelatin without said material. a

56. An intermediate for forming photoemulsions, comprlsing a mixture ofgelatin and an :independent biochemical sensitizing material inconcentrated form said intermediate having the property of forminggelatino-silverhalide emulsions of higher light-sensitiveness butsubstantially the same grain size characteristics as those formed underparallel conditions from said gelatin without said material; 1

57. An intermediate for use'in making photographic emulsions comprisingan emulsion-forming colloid and an independent sensitizing materialwithout dye sensitizing action, said intermediate havin the property offorming emulsions of big er light sensitiveness than those formed underparallel conditions from said colloid without said material.

58. An intermediate for forming hotographic gelatino-silver-halide emusions, comprising a mixture of gelatm and an mdependent sensitizingmaterial in concen-.

trated forin, said intermediate having the property of forminggelatino-silver-halide emulsions of, higher light sensitiveness, ir-vrespective of the action of dyes and morganic sensitizers, than thoseformed under said tissues and from bulky products thereof and capable ofincreasing the light sensitiveness of said emulsions before silver saltsor halid salts are incorporated therein.

60. In the process of preparing an inter-' mediate for the manufactureof photographic emulsions the step of incorporating in a biochemicalemulsion-forming colloid an independent biochemical sensitizing materialdifferent from said colloid derived from a biochemical source but havinga higher concentration of active sensitizing bodies than said source,and having the property of increasing the light sensitiveness ofv saidemulsions. I

61. In the process of preparing an intermediate for the manufacture ofphotographic gelatino-silver-halide emulsions the step of incorporatingin gelatin an independent sensitizin material from a gelatin source butsubstantially free from its normally associated gelatin and having theproperty of increasing the light sensitiveness of said of lncorporatingin gelatin an independent concentrated biochemical sensitizing materialwhich increases the li ht sensitiveness of said emulsions without aecting the grain size characteristics thereof.

63. In the process of preparing an intermediate for the manufacture ofgelatino-silver-halide emulsions, the step of incorporating in gelatinan independent sensitizing material which increases the lightsensitiveness of said emulsions irrespective of. the action of dyes andinorganic sensitizers. .64, In the process of manufacturing anintermediate for use in making photographic emulsions, extracting from abiochemical source a sensitizing material in a form substantially freefrom bulky associated diluents, and incorporating said material in aphotographic emulsion-forming colloid prior to the incorporation ofsilver salts or halid salts therein.

Signed at Rochester, New York this 4th day of June 1924:. t a

REUBEN F. PUNNETT.

